OpenCV
3.2.0
Open Source Computer Vision
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Classes | |
class | cv::LineIterator |
Line iterator. More... | |
Enumerations | |
enum | cv::MarkerTypes { cv::MARKER_CROSS = 0, cv::MARKER_TILTED_CROSS = 1, cv::MARKER_STAR = 2, cv::MARKER_DIAMOND = 3, cv::MARKER_SQUARE = 4, cv::MARKER_TRIANGLE_UP = 5, cv::MARKER_TRIANGLE_DOWN = 6 } |
Possible set of marker types used for the cv::drawMarker function. More... | |
Functions | |
void | cv::arrowedLine (InputOutputArray img, Point pt1, Point pt2, const Scalar &color, int thickness=1, int line_type=8, int shift=0, double tipLength=0.1) |
Draws a arrow segment pointing from the first point to the second one. More... | |
void | cv::circle (InputOutputArray img, Point center, int radius, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Draws a circle. More... | |
bool | cv::clipLine (Size imgSize, Point &pt1, Point &pt2) |
Clips the line against the image rectangle. More... | |
bool | cv::clipLine (Size2l imgSize, Point2l &pt1, Point2l &pt2) |
bool | cv::clipLine (Rect imgRect, Point &pt1, Point &pt2) |
void | cv::drawContours (InputOutputArray image, InputArrayOfArrays contours, int contourIdx, const Scalar &color, int thickness=1, int lineType=LINE_8, InputArray hierarchy=noArray(), int maxLevel=INT_MAX, Point offset=Point()) |
Draws contours outlines or filled contours. More... | |
void | cv::drawMarker (Mat &img, Point position, const Scalar &color, int markerType=MARKER_CROSS, int markerSize=20, int thickness=1, int line_type=8) |
Draws a marker on a predefined position in an image. More... | |
void | cv::ellipse (InputOutputArray img, Point center, Size axes, double angle, double startAngle, double endAngle, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Draws a simple or thick elliptic arc or fills an ellipse sector. More... | |
void | cv::ellipse (InputOutputArray img, const RotatedRect &box, const Scalar &color, int thickness=1, int lineType=LINE_8) |
void | cv::ellipse2Poly (Point center, Size axes, int angle, int arcStart, int arcEnd, int delta, std::vector< Point > &pts) |
Approximates an elliptic arc with a polyline. More... | |
void | cv::ellipse2Poly (Point2d center, Size2d axes, int angle, int arcStart, int arcEnd, int delta, std::vector< Point2d > &pts) |
void | cv::fillConvexPoly (Mat &img, const Point *pts, int npts, const Scalar &color, int lineType=LINE_8, int shift=0) |
void | cv::fillConvexPoly (InputOutputArray img, InputArray points, const Scalar &color, int lineType=LINE_8, int shift=0) |
Fills a convex polygon. More... | |
void | cv::fillPoly (Mat &img, const Point **pts, const int *npts, int ncontours, const Scalar &color, int lineType=LINE_8, int shift=0, Point offset=Point()) |
void | cv::fillPoly (InputOutputArray img, InputArrayOfArrays pts, const Scalar &color, int lineType=LINE_8, int shift=0, Point offset=Point()) |
Fills the area bounded by one or more polygons. More... | |
Size | cv::getTextSize (const String &text, int fontFace, double fontScale, int thickness, int *baseLine) |
Calculates the width and height of a text string. More... | |
void | cv::line (InputOutputArray img, Point pt1, Point pt2, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Draws a line segment connecting two points. More... | |
void | cv::polylines (Mat &img, const Point *const *pts, const int *npts, int ncontours, bool isClosed, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
void | cv::polylines (InputOutputArray img, InputArrayOfArrays pts, bool isClosed, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Draws several polygonal curves. More... | |
void | cv::putText (InputOutputArray img, const String &text, Point org, int fontFace, double fontScale, Scalar color, int thickness=1, int lineType=LINE_8, bool bottomLeftOrigin=false) |
Draws a text string. More... | |
void | cv::rectangle (InputOutputArray img, Point pt1, Point pt2, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Draws a simple, thick, or filled up-right rectangle. More... | |
void | cv::rectangle (Mat &img, Rect rec, const Scalar &color, int thickness=1, int lineType=LINE_8, int shift=0) |
Drawing functions work with matrices/images of arbitrary depth. The boundaries of the shapes can be rendered with antialiasing (implemented only for 8-bit images for now). All the functions include the parameter color that uses an RGB value (that may be constructed with the Scalar constructor ) for color images and brightness for grayscale images. For color images, the channel ordering is normally Blue, Green, Red. This is what imshow, imread, and imwrite expect. So, if you form a color using the Scalar constructor, it should look like:
\[\texttt{Scalar} (blue \_ component, green \_ component, red \_ component[, alpha \_ component])\]
If you are using your own image rendering and I/O functions, you can use any channel ordering. The drawing functions process each channel independently and do not depend on the channel order or even on the used color space. The whole image can be converted from BGR to RGB or to a different color space using cvtColor .
If a drawn figure is partially or completely outside the image, the drawing functions clip it. Also, many drawing functions can handle pixel coordinates specified with sub-pixel accuracy. This means that the coordinates can be passed as fixed-point numbers encoded as integers. The number of fractional bits is specified by the shift parameter and the real point coordinates are calculated as \(\texttt{Point}(x,y)\rightarrow\texttt{Point2f}(x*2^{-shift},y*2^{-shift})\) . This feature is especially effective when rendering antialiased shapes.
enum cv::MarkerTypes |
Possible set of marker types used for the cv::drawMarker function.
void cv::arrowedLine | ( | InputOutputArray | img, |
Point | pt1, | ||
Point | pt2, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | line_type = 8 , |
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int | shift = 0 , |
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double | tipLength = 0.1 |
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Draws a arrow segment pointing from the first point to the second one.
The function arrowedLine draws an arrow between pt1 and pt2 points in the image. See also cv::line.
img | Image. |
pt1 | The point the arrow starts from. |
pt2 | The point the arrow points to. |
color | Line color. |
thickness | Line thickness. |
line_type | Type of the line, see cv::LineTypes |
shift | Number of fractional bits in the point coordinates. |
tipLength | The length of the arrow tip in relation to the arrow length |
void cv::circle | ( | InputOutputArray | img, |
Point | center, | ||
int | radius, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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Draws a circle.
The function circle draws a simple or filled circle with a given center and radius.
img | Image where the circle is drawn. |
center | Center of the circle. |
radius | Radius of the circle. |
color | Circle color. |
thickness | Thickness of the circle outline, if positive. Negative thickness means that a filled circle is to be drawn. |
lineType | Type of the circle boundary. See the line description. |
shift | Number of fractional bits in the coordinates of the center and in the radius value. |
Clips the line against the image rectangle.
The function cv::clipLine calculates a part of the line segment that is entirely within the specified rectangle. it returns false if the line segment is completely outside the rectangle. Otherwise, it returns true .
imgSize | Image size. The image rectangle is Rect(0, 0, imgSize.width, imgSize.height) . |
pt1 | First line point. |
pt2 | Second line point. |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
imgSize | Image size. The image rectangle is Rect(0, 0, imgSize.width, imgSize.height) . |
pt1 | First line point. |
pt2 | Second line point. |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
imgRect | Image rectangle. |
pt1 | First line point. |
pt2 | Second line point. |
void cv::drawContours | ( | InputOutputArray | image, |
InputArrayOfArrays | contours, | ||
int | contourIdx, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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InputArray | hierarchy = noArray() , |
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int | maxLevel = INT_MAX , |
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Point | offset = Point() |
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Draws contours outlines or filled contours.
The function draws contour outlines in the image if \(\texttt{thickness} \ge 0\) or fills the area bounded by the contours if \(\texttt{thickness}<0\) . The example below shows how to retrieve connected components from the binary image and label them: :
image | Destination image. |
contours | All the input contours. Each contour is stored as a point vector. |
contourIdx | Parameter indicating a contour to draw. If it is negative, all the contours are drawn. |
color | Color of the contours. |
thickness | Thickness of lines the contours are drawn with. If it is negative (for example, thickness=CV_FILLED ), the contour interiors are drawn. |
lineType | Line connectivity. See cv::LineTypes. |
hierarchy | Optional information about hierarchy. It is only needed if you want to draw only some of the contours (see maxLevel ). |
maxLevel | Maximal level for drawn contours. If it is 0, only the specified contour is drawn. If it is 1, the function draws the contour(s) and all the nested contours. If it is 2, the function draws the contours, all the nested contours, all the nested-to-nested contours, and so on. This parameter is only taken into account when there is hierarchy available. |
offset | Optional contour shift parameter. Shift all the drawn contours by the specified \(\texttt{offset}=(dx,dy)\) . |
void cv::drawMarker | ( | Mat & | img, |
Point | position, | ||
const Scalar & | color, | ||
int | markerType = MARKER_CROSS , |
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int | markerSize = 20 , |
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int | thickness = 1 , |
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int | line_type = 8 |
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Draws a marker on a predefined position in an image.
The function drawMarker draws a marker on a given position in the image. For the moment several marker types are supported, see cv::MarkerTypes for more information.
img | Image. |
position | The point where the crosshair is positioned. |
color | Line color. |
markerType | The specific type of marker you want to use, see cv::MarkerTypes |
thickness | Line thickness. |
line_type | Type of the line, see cv::LineTypes |
markerSize | The length of the marker axis [default = 20 pixels] |
void cv::ellipse | ( | InputOutputArray | img, |
Point | center, | ||
Size | axes, | ||
double | angle, | ||
double | startAngle, | ||
double | endAngle, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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Draws a simple or thick elliptic arc or fills an ellipse sector.
The function cv::ellipse with less parameters draws an ellipse outline, a filled ellipse, an elliptic arc, or a filled ellipse sector. A piecewise-linear curve is used to approximate the elliptic arc boundary. If you need more control of the ellipse rendering, you can retrieve the curve using ellipse2Poly and then render it with polylines or fill it with fillPoly . If you use the first variant of the function and want to draw the whole ellipse, not an arc, pass startAngle=0 and endAngle=360 . The figure below explains the meaning of the parameters.
img | Image. |
center | Center of the ellipse. |
axes | Half of the size of the ellipse main axes. |
angle | Ellipse rotation angle in degrees. |
startAngle | Starting angle of the elliptic arc in degrees. |
endAngle | Ending angle of the elliptic arc in degrees. |
color | Ellipse color. |
thickness | Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a filled ellipse sector is to be drawn. |
lineType | Type of the ellipse boundary. See the line description. |
shift | Number of fractional bits in the coordinates of the center and values of axes. |
void cv::ellipse | ( | InputOutputArray | img, |
const RotatedRect & | box, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
img | Image. |
box | Alternative ellipse representation via RotatedRect. This means that the function draws an ellipse inscribed in the rotated rectangle. |
color | Ellipse color. |
thickness | Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a filled ellipse sector is to be drawn. |
lineType | Type of the ellipse boundary. See the line description. |
void cv::ellipse2Poly | ( | Point | center, |
Size | axes, | ||
int | angle, | ||
int | arcStart, | ||
int | arcEnd, | ||
int | delta, | ||
std::vector< Point > & | pts | ||
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Approximates an elliptic arc with a polyline.
The function ellipse2Poly computes the vertices of a polyline that approximates the specified elliptic arc. It is used by cv::ellipse.
center | Center of the arc. |
axes | Half of the size of the ellipse main axes. See the ellipse for details. |
angle | Rotation angle of the ellipse in degrees. See the ellipse for details. |
arcStart | Starting angle of the elliptic arc in degrees. |
arcEnd | Ending angle of the elliptic arc in degrees. |
delta | Angle between the subsequent polyline vertices. It defines the approximation accuracy. |
pts | Output vector of polyline vertices. |
void cv::ellipse2Poly | ( | Point2d | center, |
Size2d | axes, | ||
int | angle, | ||
int | arcStart, | ||
int | arcEnd, | ||
int | delta, | ||
std::vector< Point2d > & | pts | ||
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
center | Center of the arc. |
axes | Half of the size of the ellipse main axes. See the ellipse for details. |
angle | Rotation angle of the ellipse in degrees. See the ellipse for details. |
arcStart | Starting angle of the elliptic arc in degrees. |
arcEnd | Ending angle of the elliptic arc in degrees. |
delta | Angle between the subsequent polyline vertices. It defines the approximation accuracy. |
pts | Output vector of polyline vertices. |
void cv::fillConvexPoly | ( | Mat & | img, |
const Point * | pts, | ||
int | npts, | ||
const Scalar & | color, | ||
int | lineType = LINE_8 , |
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int | shift = 0 |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void cv::fillConvexPoly | ( | InputOutputArray | img, |
InputArray | points, | ||
const Scalar & | color, | ||
int | lineType = LINE_8 , |
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int | shift = 0 |
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Fills a convex polygon.
The function fillConvexPoly draws a filled convex polygon. This function is much faster than the function cv::fillPoly . It can fill not only convex polygons but any monotonic polygon without self-intersections, that is, a polygon whose contour intersects every horizontal line (scan line) twice at the most (though, its top-most and/or the bottom edge could be horizontal).
img | Image. |
points | Polygon vertices. |
color | Polygon color. |
lineType | Type of the polygon boundaries. See the line description. |
shift | Number of fractional bits in the vertex coordinates. |
void cv::fillPoly | ( | Mat & | img, |
const Point ** | pts, | ||
const int * | npts, | ||
int | ncontours, | ||
const Scalar & | color, | ||
int | lineType = LINE_8 , |
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int | shift = 0 , |
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Point | offset = Point() |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void cv::fillPoly | ( | InputOutputArray | img, |
InputArrayOfArrays | pts, | ||
const Scalar & | color, | ||
int | lineType = LINE_8 , |
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int | shift = 0 , |
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Point | offset = Point() |
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Fills the area bounded by one or more polygons.
The function fillPoly fills an area bounded by several polygonal contours. The function can fill complex areas, for example, areas with holes, contours with self-intersections (some of their parts), and so forth.
img | Image. |
pts | Array of polygons where each polygon is represented as an array of points. |
color | Polygon color. |
lineType | Type of the polygon boundaries. See the line description. |
shift | Number of fractional bits in the vertex coordinates. |
offset | Optional offset of all points of the contours. |
Size cv::getTextSize | ( | const String & | text, |
int | fontFace, | ||
double | fontScale, | ||
int | thickness, | ||
int * | baseLine | ||
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Calculates the width and height of a text string.
The function getTextSize calculates and returns the size of a box that contains the specified text. That is, the following code renders some text, the tight box surrounding it, and the baseline: :
text | Input text string. | |
fontFace | Font to use, see cv::HersheyFonts. | |
fontScale | Font scale factor that is multiplied by the font-specific base size. | |
thickness | Thickness of lines used to render the text. See putText for details. | |
[out] | baseLine | y-coordinate of the baseline relative to the bottom-most text point. |
void cv::line | ( | InputOutputArray | img, |
Point | pt1, | ||
Point | pt2, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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Draws a line segment connecting two points.
The function line draws the line segment between pt1 and pt2 points in the image. The line is clipped by the image boundaries. For non-antialiased lines with integer coordinates, the 8-connected or 4-connected Bresenham algorithm is used. Thick lines are drawn with rounding endings. Antialiased lines are drawn using Gaussian filtering.
img | Image. |
pt1 | First point of the line segment. |
pt2 | Second point of the line segment. |
color | Line color. |
thickness | Line thickness. |
lineType | Type of the line, see cv::LineTypes. |
shift | Number of fractional bits in the point coordinates. |
void cv::polylines | ( | Mat & | img, |
const Point *const * | pts, | ||
const int * | npts, | ||
int | ncontours, | ||
bool | isClosed, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void cv::polylines | ( | InputOutputArray | img, |
InputArrayOfArrays | pts, | ||
bool | isClosed, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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Draws several polygonal curves.
img | Image. |
pts | Array of polygonal curves. |
isClosed | Flag indicating whether the drawn polylines are closed or not. If they are closed, the function draws a line from the last vertex of each curve to its first vertex. |
color | Polyline color. |
thickness | Thickness of the polyline edges. |
lineType | Type of the line segments. See the line description. |
shift | Number of fractional bits in the vertex coordinates. |
The function polylines draws one or more polygonal curves.
void cv::putText | ( | InputOutputArray | img, |
const String & | text, | ||
Point | org, | ||
int | fontFace, | ||
double | fontScale, | ||
Scalar | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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bool | bottomLeftOrigin = false |
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Draws a text string.
The function putText renders the specified text string in the image. Symbols that cannot be rendered using the specified font are replaced by question marks. See getTextSize for a text rendering code example.
img | Image. |
text | Text string to be drawn. |
org | Bottom-left corner of the text string in the image. |
fontFace | Font type, see cv::HersheyFonts. |
fontScale | Font scale factor that is multiplied by the font-specific base size. |
color | Text color. |
thickness | Thickness of the lines used to draw a text. |
lineType | Line type. See the line for details. |
bottomLeftOrigin | When true, the image data origin is at the bottom-left corner. Otherwise, it is at the top-left corner. |
void cv::rectangle | ( | InputOutputArray | img, |
Point | pt1, | ||
Point | pt2, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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Draws a simple, thick, or filled up-right rectangle.
The function rectangle draws a rectangle outline or a filled rectangle whose two opposite corners are pt1 and pt2.
img | Image. |
pt1 | Vertex of the rectangle. |
pt2 | Vertex of the rectangle opposite to pt1 . |
color | Rectangle color or brightness (grayscale image). |
thickness | Thickness of lines that make up the rectangle. Negative values, like CV_FILLED , mean that the function has to draw a filled rectangle. |
lineType | Type of the line. See the line description. |
shift | Number of fractional bits in the point coordinates. |
void cv::rectangle | ( | Mat & | img, |
Rect | rec, | ||
const Scalar & | color, | ||
int | thickness = 1 , |
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int | lineType = LINE_8 , |
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int | shift = 0 |
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This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
use rec
parameter as alternative specification of the drawn rectangle: r.tl() and r.br()-Point(1,1)
are opposite corners